As regards a technique for the production of high-density, high-strength silicon carbide sintered bodies, there have hitherto been proposed a method described in Japanese Patent Application Publication No. 57-32,035 in which .beta.-type silicon carbide (hereinafter abbreviated as ".beta.-SiC") powder is used as a starting material and fired together with a B compound and a compound as a sintering aid, a method of using .alpha.-type silicon carbide (hereinafter abbreviated as ".alpha.-SiC") powder as a starting material as described in Japanese Patent Application Publication No. 58-14,390, and the like.
In the case of the aforementioned conventional techniques, high density is realized, but the control of .beta..fwdarw..alpha. transformation and the control of crystal grain growth at the firing stage are insufficient and. Hence the strength of the resulting sintered body is insufficient for putting into practical use.